Robert Bruce Stewart was born in London, England, in 1813, the son of David Stewart Martha Mann Hill. Robert Bruce received much of his education in the Arts and Sciences independently but was trained as a land agent and surveyor by his father. In London on 27 June 1838, Robert Bruce married Helen Birnie, daughter of the Prince Edward Island merchant, George Birnie. Robert Bruce, along with his wife and their five children left Britain on 29 August 1846 to settle in Charlottetown, PEI. In 1863, Robert Bruce moved his family, now including nine children, to a country estate called Strathgartney on the Stewart property in Lot 30.

Upon his father's death in 1852, Robert Bruce Stewart became the largest resident proprietor on PEI, owning more than 67,000 acres . He was one of the key players in the Land Question on PEI, fighting long and hard against the Land Purchase Act by which the government would purchase all large land holdings from the proprietors which were to be sold to tenants. In February 1876, Robert Bruce was forced to sell all but 500 acres of his vast estate to the PEI government. Thereafter, Robert Bruce left his Strathgartney home and retired to Charlottetown where he lived with his second wife, Harriet Amelia Mayne, whom he married 7 December 1876. Robert Bruce Stewart died in Charlottetown 9 May 1884.